Conventionally, various wireless communication systems, such as PDC (Personal Digital Cellular), W-CDMA (Wideband Code Division Multiple Access), cdma20001x, PHS (Personal Handy-phone System), wireless LAN (Local Area Network), Bluetooth and the like are operated as a mobile communication system and standardization of hi-speed wireless communication such as WiMAX (Worldwide Interoperability for Microwave Access) is also promoted. Each of the wireless communication systems has a different characteristic.
For example, PHS has an advantage that a large number of terminals usable per area can be provided and usability efficiency of frequency is high, since a cell area is small. Since a PHS terminal has to receive only an individual PCH (Paging Channel), while capturing CS (Cell Station) and its interval is long, it is an advantage that waiting time is long. However, it is a disadvantage that a possibility of an interruption of communication is high, if a communication is made while moving at a high speed, since an area covered by a cell is small.
On the contrary, for example, in W-CDMA, a cell area is large, so that it is possible to use it within a large distance range while moving at a high speed. However, the waiting time is considerably short compared to the PHS terminal, since a W-CDMA terminal performs a reverse-spreading process and the like even in monitoring a call reception or a signal level of a cell and the like.
Further, in wireless LAN represented by broadly used IEEE (Institute of Electrical and Electronic Engineers) 802.11b, a hot spot is placed in a coffee shop or a public facility and the like, and the communication at a maximum of 11 Mbps can be performed. However, a cell area is small and about 10 m in radius, since the wireless LAN is supposed to be used inside.
Recently, a portable communication terminal for multi mode is also considered, in which different wireless communication systems can be used seamlessly. For example, Japanese Patent Application Laid-Open No. 2004-235863 discloses a portable communication terminal in which wireless communication systems are switched over depending on a moving speed of the terminal or by determining a waiting time length in the plurality of wireless communication systems based on a residual battery charge.